| Date | May 2016 | Marks available | 2 | Reference code | 16M.3.hl.TZ0.6 |
| Level | HL | Paper | 3 | Time zone | TZ0 |
| Command term | Deduce and State | Question number | 6 | Adapted from | N/A |
Question
Biphenyl nitriles, such as the molecule shown below, were the first thermotropic liquid crystal molecules to be synthesized.
(i) The monomers from which Kevlar® is produced are given below.
Deduce the formula of the repeating unit of Kevlar®.
(ii) State the structural feature of Kevlar® that is primarily responsible for its strength.
Markscheme
(i)
—COC6H4CONHC6H4NH—
Continuation bonds are necessary for the mark but brackets and n can be ignored. If more than one repeating unit is drawn, do not award the mark.
(ii)
H bonds «form between chains from NH of one chain to CO of the next»
Examiners report
[N/A]
